#include <iostream>
using namespace std;
int n,w[100],sum,x[10000];
int main(){
    cin>>n;
    x[0]=1;
    for(int i=0;i<n;i++){
        cin>>w[i];
        sum+=w[i];
    }
    if(sum%2){
        cout<<"impossible\n";
        return 0;
    }
    for(int i=0;i<n;i++){
        for(int j=sum/2;j>=w[i];j--){
            x[j]=(x[j-w[i]]|x[j]);
        }
    }
    cout<<(x[sum/2]?"":"im")<<"possible\n";
    return 0;
}